class Solution {
public:
    int minDistance(string word1, string word2) {
        int m = word1.size(), n = word2.size();

        vector<vector<int>> dp(m + 1, vector<int>(n + 1, 0));
        for (int i = 0; i <= m; i++) dp[i][0] = i;
        for (int i = 0; i <= n; i++) dp[0][i] = i;

        for (int i = 1; i <= m; i++) {
            for (int j = 1; j <= n; j++) {
                int tmp1 = dp[i - 1][j];
                int tmp2 = dp[i][j - 1];
                int tmp3 = dp[i - 1][j - 1];
                if (word1[i - 1] != word2[j - 1]) tmp3 += 1;
                dp[i][j] = min(tmp1 + 1, min(tmp2 + 1, tmp3));
            }
        }
        return dp[m][n];
    }
};
